Superabsorbent Polymer Particles Coated With A Hydrophilic Elastomer And Absorbent Article Comprising Such Particles

Abstract

Superabsorbent polymer particles, coated with a block copolymer comprising at least four blocks being at least two hard blocks, one soft block and one hydrophilic block, wherein a the soft block is sandwiched between the hard blocks.

Description

CROSS REFERENCE TO RELATED APPLICATION[0001]This application claims the benefit of U.S. Provisional Application No. 61 / 359,123, filed on Jun. 28, 2010.FIELD OF THE INVENTION[0002]The invention relates to superabsorbent material, such as superabsorbent polymer particles, comprising a hydrophilic elastomeric water vapor permeable coating. The coating is intended to allow swelling of the coated superabsorbent polymer particles without breakage of the coating, and, at the same time ensure good transport of water based liquids through the coating into the superabsorbent polymer particle.[0003]The invention also relates to diapers, adult incontinence articles and catamenial devices, such as sanitary napkins, comprising said coated water swellable material.[0004]The invention further relates to a process of making such a superabsorbent material comprising the hydrophilic elastomeric water vapor permeable coating.BACKGROUND OF THE INVENTION[0005]An important component of disposable absorben...

AI Technical Summary

Benefits of technology

[0015]Without wishing to be bound by theory, it is believed that due to the specific selection of the four or more blocks of the block copolymer a coating providing good liquid transport into the superabsorbent particles, paired with good stability of the coating which can help to accommodate expansion of the superabsorbent particle can be achieved.

[0016]It is, for example, believed that the good liquid transport through the coating is positively influenced by the high water vapor transmission rate of the block copolymers, and that the good stability of the coating results from its elastic extensibility.

Problems solved by technology

The gel strength needs to be high enough in the absorbent article so that the superabsorbent polymer particles do not deform and fill the capillary void spaces to an unacceptable degree causing so-called gel blocking This gel-blocking inhibits the rate of fluid uptake or the fluid distribution, i.e. once gel-blocking occurs, it can substantially impede the distribution of fluids to relatively dry zones or regions in the absorbent article and leakage from the absorbent article can take place well before the superabsorbent polymer particles are fully saturated or before the fluid can diffuse or wick past the “blocking” particles into the rest of the absorbent article.

Superabsorbent polymers with relatively high permeability can be made by increasing the level of internal crosslinking or surface crosslinking, which increases the resistance of the swollen gel against deformation by an external pressure such as the pressure caused by the wearer, but this typically also reduces the absorbent capacity of the gel undesirably.

Often the surface crosslinked superabsorbent polymer particles are constrained by the surface-crosslinking ‘shell’ and cannot absorb and swell sufficiently, and / or that the shell is not strong enough to withstand the stresses of swelling or the stresses associated with performance under load.

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